General: Roof access hatch shall be model WB-RH 30x36 steel manufactured exclusively for The Williams Brothers Corporation
of America, with a durable, re-coatable gray primer finish. A yellow and black striped visual warning signal shall be on top of curb
and on inside of lid.
Curb Construction: Curb shall be 14 gauge (G 90) galvanized steel with durable re-coatable gray primer finish standard.
Curb shall be 12" (304mm) in height with a 4" (101mm) fiber board insulation, and mounting holes for roof attachment. Curb shall have
integral cap flashing of the same material and thickness as the curb. Curb and cap flashing shall be fully welded at the corners for
a watertight construction. Hinges are two-piece formed steel, with a non-removable heavy-duty pivot pin.
Covers: Cover shall be 14 gauge (G 90) galvanized steel, with radius corners for safety, and shall be fully welded
at the corners for watertight construction. The cover liner shall be 22 gauge. The cover shall be insulated with a 1” (25.4mm) thick
fiberglass insulation, and reinforced as required to support a 40#/ft square live load. An extruded rubber gasket, mechanically fastened
to the inside of the lid shall cause the hatch lid to seal.
Hardware: Hardware shall include interior handle, with a positive, one-point locking mechanism, exterior
handle, and provisions for padlock, both inside and out. Pre-lubricated compression springs, encased in zinc-plated telescopic tubes,
for smooth and controlled door operation at any position. An automatic, hold-open arm, with vinyl grip, shall be standard. All hardware
shall be corrosion resistant, and all fasteners shall be of a self-locking type.